INCORPORATION BY REFERENCE: Applicant(s) hereby incorporate herein by reference, any and all U.S. patents, U.S. patent applications, and other documents and printed matter cited or referred to in this application.
1. Field of the Invention
This invention relates generally to tube working dies and more particularly to a roller die for compressing or reducing the size of a square or rectangular tube and especially for compressing one end of a square tube for adapting the end for being inserted into a non-reduced tube end of the same size tubing.
2. Description of Related Art
The following art defines the present state of this field:
Omerza, U.S. Des. No. 397,601 describes a design buffer for buffing round articles.
Schrepfer, U.S. Des. No. 400,895 describes a design for a roller mill.
Elting, U.S. Pat. No. 1,890,077 describes the art of constructing sheet metal tubing comprising kneading parts of the material of a sheet to be formed into tubing while preserving the sheet in a straight condition, and then shaping the sheet into tubing.
Layton, U.S. Pat. No. 2,059,124 describes a combination of a forging die having a billet-receiving opening of predetermined cross-sectional dimensions, a preshaping device adapted to receive a billet of greater diagonal dimensions cross-sectionally of the billet than the largest cross-sectional measurement of the die opening and comprising means arranged to engage the diagonal corners solely of said billet to press said corners radially toward the longitudinal axis of the billet simultaneously and simultaneously bulging the billet radially between said corners to measurements less than said dimensions of the die opening, and means for passing a billet through said device to preshape the billet preparatory to its entrance into the die.
Dvorak, U.S. Pat. No. 2,207,245 describes a method of drawing tubes from hollow blanks fitted on a mandrel comprising drawing longitudinal grooves in sections distributed on the outside of the work, drawing the work through a caliber formed by freely rotatable drawing rollers arranged in such manner that the edges of their operative surfaces meet over the longitudinal grooves previously formed in the work, drawing the work through freely rotatable pressure rollers arranged around the work in angular displacement with reference to the said drawing rollers in order to slightly enlarge the diameter of the work and to thus separate the inside wall of the work from the mandrel, the foregoing operations being performed at the first work station, and repeating said, operations at successive work stations spaced apart a distance at least greater than the length of the work on the mandrel after having passed through the preceding work station.
Frankenberg, U.S. Pat. No. 3,736,846 describes a container body maker including means for forming a completed cylindrical container body and a means for reshaping the cylindrical container body. The reshaping means includes angularly spaced posts arranged to support the cylindrical container and bending means disposed between the posts. The bending means serve to depress the portions of the cylindrical body spanning the posts to reshape the body.
Zacharias, U.S. Pat. No. 4,255,956 describes an apparatus for sizing square metal ingots to be subsequently pierced in a push bench to form pierced blanks for rolling into tubes having freely rotatable sizing rolls to engage the corner edges of the ingot as the ingot is pushed through the support and freely rotatable guiding rollers to engage the side faces of the ingot. The sizing rolls are radially adjustable by means of both a coarse adjustment device and a fine adjustment device while the guiding rollers are only provided with coarse adjustment.
The adjustment devices can be computer controlled so that both ends of the ingot are conically tipped and so that the ingot is slightly tapered throughout its length.
Sakaya, et al, U.S. Pat. No. 5,054,196 describes a wick layer that is attached and fixed to one surface of a metal tape without forming a gap with the metal surface, and thereafter, the tape is rolled so that the surface having the wick layer serves as an inner surface, thus forming a pipe shape, then the pipe wall is corrugated. According to the above process, the wick layer is completely and uniformly attached to the inner surface of the heat pipe.
Soder, U.S. Pat. No. 5,907,969 describes a tool for working a shaped metal tube, such as a square or rectangular metal tube, having a hollow interior and an outer surface to produce an end reduction in the tube. The tool includes a head having a longitudinally extending interior cavity and a plurality of roller cavities, each communicating with the interior cavity. A plurality of grooved rollers are rotatably mounted within the head, one within each of the roller cavities. Each of the grooved rollers has a periphery extending into the interior cavity and configured to engage a portion of the outer surface of the tube to be reduced, such as a corner portion of a square tube. Depending upon the shape of the tube being reduced, the tool may further include a pair of flat-area rollers. The flat-area rollers may be used to engage the relatively long sides of a rectangular tube. The tool further includes a mandrel disposed within the interior cavity of the head and spaced apart from the periphery of each of the rollers, with the mandrel being effective for preventing the tube from collapsing as a result of the end reduction. The tool may also include a rake which is effective for maintaining the shape of the end of the tube being reduced.
The prior art teaches apparatus for reducing the diagonal dimensions of a rectangular billet, rolling mills with diametrically opposed rollers for reshaping the corners of a tube or billet, a method for depressing portions of a cylindrical tube, a machine adapted for forming a groove along the length of a pipe, and designs for rolling mills and buffing machines, but does not teach a simplified apparatus and method for reducing the size of an end of a sheet metal tube. The present invention fulfills these needs and provides further related advantages as described in the following summary.